Saturday, June 29, 2013

The Old State House is where the British Government held its sessions in Boston back in the 18th century. Today, it's part of the Freedom Trail in Boston and it is also the State Street Subway Station (under the State House). How the built the subway station under a historical place like this is amazing to me, but that's another story.

Of relevance to me is that the intersection is a amazing number of streets coming together and a good example of a pedestrian scramble. I am not a strong proponent of the Barnes' Dance (as they are also know), but this is a great example of where it makes a lot of sense because of the intensity of pedestrian traffic, the interest in crossing the street in so many different directions and it is the "there" there. Pedestrian safety is the highest priority and in this case with all of the potential for conflicts between pedestrians and right turning traffic, this is a great solution to a relatively unique problem.

The subway also brings a heavy peak flow from the transit station to the surrounding area when a train arrives in the station. I would imagine in the morning that this place is active with a lot of people hustling to work.

The other reason this makes a lot of sense is the extent of tourist traffic. The number of tourists in this part of downtown Boston suggests another reason to use the pedestrian scramble. In general, pedestrian scrambles can result in higher delay for people walking (and others) because of the time necessary to separate the movements.

Thursday, June 27, 2013

There was an impromptu opportunity to discuss the traffic operations benefits of bike boxes. The following was what was shown during the discussion about bicycle boxes at the National Committee on Uniform Traffic Control Devices where it became apparent that there are professionals that help write the MUTCD that haven't had the experience of a significant number of cyclists where a bike box would provide a traffic operations benefit.

This particular bicycle box at the intersection of SE Madison & Grand Avenue in Portland is not a standard design because the bike lane is to the left of the right turn lane, but it does provide the additional space at the intersection for clearing the queue of bicycles. If you're not familiar with the bicycle box, background information is provided at the National Association of City Transportation Officials (NACTO) website under the Intersections tag of the Urban Bikeway Design Guide.

This series of photos shows how the people on bikes queue up in the bicycle box. The sequence of photos also shows that 10 people on bikes cross through the intersection in 12 seconds (this is assuming some startup lost time). Portland State University just recently completed research on this particular situation and quantified the benefits of the bike box by comparing the situation of flow with the flow at the single bicycle lane and the the bicycle box which provides more space for moving bikes that have queued up during the red.

This example is a non standard location at SE Madison & Grand Avenue. The benefit is for the very busy bus traffic and right turning volume that is at the intersection.

Upstream of the bicycle box (250' from the stop bar at SE 6th)
Right turn develops farside of the intersection

Bicycle lane between right turn lane and through travel lane

Bicycle box with three people stacked in box
(Depth of box is 14' standard in Portland)

One of the elements that FHWA staff and the Signals folks raised at the end of the dialogue was the problems as they saw them with the combination of stop signs and the pedestrian hybrid beacon side street display. They believe that the combination of a stop sign and a bicycle traffic signal is in direct conflict and therefore should be strictly prohibited in the MUTCD (shall statement). I highlighted that we have not had an operational problem with this configuration at our two locations and we're planning to build two more (SE 19th & Tacoma and E 53rd & Burnside). This is similar to the complaint with the Half Signals. In the streamlining effort of the Manual, it was pointed out that Half Signals are no longer strictly prohibited. The intent is that the Pedestrian Hybrid Beacon would specifically prohibit bicycle signals being part of the installation. There was also specific feedback that Portland received with how the display was using flashing red and not to use the wig wag operation (wig wag is reserved for railroad signals in all other cases).

There was also the argument that beacons should not be at intersections. The fundamental research on the topic was focused in Tucson where they have deployed more than 80 beacons and they are mostly at intersections. There has been some conversation about eliminating that should not statement based on feedback from Tucson and other communities.

Portland Signals staff had concerns related to the pedestrian countdown timer and the safety of a person (running or cycling) arriving during the flashing don't walk countdown. There are some that are not interested in the argument as engineers often think of these crossing events as singular in nature (limited walking and cycling occurs in their communities?), so the late arriving person should just wait for the next opportunity and not cross on the Flashing Don't Walk.

The other element for bicycle signals that FHWA wanted the National Committee and the Task Force to consider was the inclusion of warrants. The warrants used in the California MUTCD are captured below. The entire CA MUTCD can be found here.

The one problem I see with the warrants (this is likely why there isn't a proliferation of bicycle signals in CA) is the need for >50 bicycles at a particular location. If there's no crossing opportunity now, it will be likely to not have 50 crossings. If the anticipation or projection of bicycle volumes is allowed than this isn't as significant of a barrier.

I confirmed with FHWA staff that the City of Portland's implementation of a bicycle signal at a pedestrian hybrid beacon is still under experimental review, if this prohibition comes to pass, the City would be notified.

Wednesday, June 26, 2013

I rode my rental bicycle on the East Coast Greenway Trail this morning prior to the National Committee on Uniform Traffic Devices to get geared up. It was a nice way to warm up to the full day of discussion about bicycle technical details that would be discussed throughout the day in what turned out to be 10 hours of discussion.

The first crossing that struck me was the solar powered circular beacons. These were frequent at some of the busier crossings on the corridor with the busy part being the vehicle traffic.

The lower volume crossings used a wide variety of non-uniform traffic markings and some signs that were against the state law, which in Maine is for people driving to yield to pedestrians (as opposed to coming to a complete stop).

This is one of my favorite series of signs that indicate the historic use of space in Boston's streetscape. The first sign confirms to people that bicycles have the right to use the full lane. The sign below clarifies to motor vehicle operators (?) to Change Lanes to Pass (could people on bikes do this too during congestion?) and just one more sign to clarify that people on bikes are supposed to "RIDE WITH TRAFFIC". Clearly, the 12" fog line striping is not suitable for riding a bicycle, so the sign is an apparent attempt to codify what is already happening on the facility. the lane widths seem ample and seem like they could be revised to provide a bicycle lane.You can see the next set of signs downstream of the intersection. The CARS ONLY overhead sign is to warn trucks that they should not be in these lanes, but as a multimodal transportation professional what comes to mind is whether bicycles or motorcycle traffic is not supposed to be in those lanes.

The sign is unlikely to be necessary because there is also the low clearance sign overhead. In the second photo, you can see a person on a bike in the lane, but the other cyclists that I saw as I was walking to the train station, were up on the sidewalk sharing the space with people that were walking into the City from the Science Museum. A separate angle on the lane striping at the intersection was worth noting. The application of a sharrow on the lane line is something I haven't seen before. It isn't likely an innovative new treatment, but rather a mistake. I didn't do an assessment to understand which striping came first. I doubt that the intent is to have people on bicycles to split the lanes on the approach to the traffic signal, but I am wondering if an expert witness could make that case.The last example of striping comes at the intersection downstream and a common problem for cities. My solution for this in Portland is to be out on the streets and make sure that I capture these issues and get the private contractors or city Bureaus to restore the striping that they damage as a part of their project. Oftentimes, the temporary pavement is left for awhile (especially during the winter) and it is an unfortunate condition when we stress the importance of markings at the National Committee on Uniform Traffic Control Devices.

I was considering the question I fielded at the Livable Streets Talk last night and came across this excerpt from the NCHRP 562 report that is worth citing in the future.

Distance to Nearest Traffic Signal. The current(pre-2006) MUTCD includes a provision that a signal shall not be considered at locations within 300 ft (91 m) of another signal. This is believed to be based on the distance a pedestrian will walk in order to cross the major street. The researchers did not identify data that support this distance or other distances of how far beyond the desired path a pedestrian would be willing to walk. The USDOT’s 1995 Nationwide Personal Transportation Survey did find that most pedestrian trips (73 percent) are 0.5 mi (0.8 km) or less.With most trips being about 2,600 ft (792 m), pedestrians might not be willing to increase their trip length by more than 10 percent in order to walk to a different crossing location. As part of the on-street pedestrian surveys documented in Appendix K, those interviewed were asked “if this crossing was not here, would you walk to the next intersection (point to intersection of interest)?”For three of the sites, only about 25 percent of the respondents would walk to a signalized intersection at 550, 950, or 1,000 ft (168, 290, or 305 m). For the site with a signalized intersection about 200 ft (61 m) from the crossing, about 50 percent of those interviewed would walk to that crossing. The remaining site where this question was appropriate did not follow similar findings. A much higher percentage indicated that they would be willing to walk to another crossing. Over 65 percent of the respondents indicated that they would walk 600 ft (183 m) to cross at a signalized crossing. The number of individuals willing to walk such a distance was influenced by the number of lanes at the site (six lanes), speed and volume of traffic (high), and existing treatment (marked crosswalk only). Several of the respondents selected “yes” to the question and then commented that they walk to the nearby crossing “most of the time” or “sometimes” depending on the weather or other factors.
A future research effort should consider the same question for people on bicycles. Presumably, the speed of a cyclists expands the distance somewhat, but behavior seems largely sensitive to perceived risk.

The treatments in Cambridge seemed to be an effort that has been significant in the past several years. The first intersection I encountered was a pedestrian signal outside of the "T" station at Cambridge Center adjacent to the MIT Co-op bookstore. The pedestrian refuge was sufficient to allow people to wait. There was a push button on either side of the street, but most people weren't bothering to push the button because the traffic was fairly slow and the risk of crossing against the signal was limited.
The state las in Massachusettes appear to be yield to pedestrians, which was reinforced many times with supplementary signs in the road and like these that are more substantial pole mounted signs.
I was reviewing the FHWA website on the topic of Safety at Unsignalized Intersections and the information is dated and could stand an update. The work completed by the National Cooperative Highway Research Program NCHRP 562/Transit Cooperative Research Program serves to provide a more urban focus that is applicable for communities like Cambridge and Portland.
As I walked through Cambridge I came across pedestrian scramble installations and the City uses leading pedestrian intervals (LPI) at most all of the traffic signals. The LPI is a very short duration (most I saw were 3 seconds) which is significant in a cycle length as short as 90 seconds. The City also timed the walk with the countdown, which I argue limits your ability to provide transit signal priority because of the lack of intelligence in the countdown pedestrian indications (they simply repeat the interval in the controller that is flashing don't walk from the previous cycle).

Bike lanes were ubiquitous in Cambridge and the City was bikeable. I was a bit surprised to see as much bike traffic as there was and part of the traffic was on the City bikeshare system.
One of the detractions of the system in Cambridge was the amount of construction that was happening due to the biotech sector growth surrounding the campuses of MIT and Northeastern University. The construction was commonly happening with barrels in the bike lane and often restriction of pedestrian crossings. We have the same problem in the City of Portland, but it was something that clearly was happening on some of the busier bicycle corridors.
One treatment that was different than we would use in Portland was the Bicycles May Use Full Lane sign.

I flew to Boston en route to the National Committee Meeting for the Manual of Uniform Traffic Control Devices. The opportunity provided a chance to talk at the Livable Streets Alliance about the "Confessions of a Traffic Engineer: The Misuse of Level of Service and its Impact on Active Transportation". It was enjoyable to share some of the ideas we've developed in Portland about transportation policy with the group. The effort was a fundraiser for the programs that Livable Streets puts on which makes me happy that I can contribute to the work in the advocacy community.
The ideas of making safety the priority for transportation design resonated with the audience. One of the most challenging questions related to the ethics of designing unsafe conditions for pedestrians. The transportation engineering industry knows that a four lane cross section and 45 mph speed arterial is dangerous for pedestrians that are crossing at an unsignalized intersection, which is a legal crossing. The
topic of whether our knowledge of the potential for unsafe conditions creates an ethical dilemma was something I haven't had a lot of conversations about. It's worth identifying this sort of relationship as part of a wider conversation. It would be difficult to make the link without clarity related to the conditions. There are some instances where the location of a nearby signal or enhanced treatment (rapid flash beacon, etc) would be sufficient. But how far is sufficient? What's the out of direction travel that is reasonable. State DOTs often require a significant distance between signals on state highways in the name of access management. Streetlighting may also be limited because the agency doesn't want to pay the long term costs of maintenance and operations of the electricity. What should we ask developers to do and should this be consistent with what we do on our projects? If not, how do we justify our actions? More discussion is needed, but this was a fun group to start the conversation with.
Here's how my hosts marketed the talk:

What is the difference between congestion and "failure" in transportation?How does measuring vehicles instead of people at intersections affect the way our streets are designed? Are safety, economic development and livability taken into account in federal standard highway design manuals?

The transportation engineering community is advancing road design concepts that encourage active transportation, but new approaches and standards have not yet been widely adopted. Come hear Peter Koonce, from City of Portland Bureau of Transportation, speak to the challenges and identify design approaches that would allow the development of a balanced transportation system that better embodies local community policy and needs. Portland, Oregon will be used as a case study to show how the City was able to prioritize its own design policy over national "Level of Service" thresholds.

Cambridge, MA was one of the earliest adopters of cycletracks in the U.S. and this was my first time cycling on the facility which is adjacent to the MIT campus. The cycletrack was enjoyable to ride on and reminded me of many of the Dutch cycletracks I had used last summer or the one way facilities common in Copenhagen. The nature of having the cycling facility flush with the driveway (which is lower speed traffic) is a nice touch. The markings at the driveway denote the potential for a conflict or a transition at the locations where the cycletrack is ending.
The City was using the blue markings prior to the feedback the City of Portland got related to using green and apparently they haven't had the need to go back and refresh the markings.
The treatment that was worth noting was the yield to bikes sign and the lane configuration sign which included the blue bike lane to indicate to motorists that the lane exists and there should be an awareness of the potential for a conflict. The first time I saw the sign, I had a hard time noting the bike marking in the lane, the black and blue does not provide a very good contrast that is easy to pick up and doesn't offer a consistent marking for the bike symbol, I tend to prefer the addition of the rider to match the striping, but that's a detail that's something to talk with the Manual of Uniform Traffic Control Devices (MUTCD) National Committee about this week.
This post reminded me of the early work done by Alta to summarize some of the facilities in 2009, which seemed like an eternity ago what with the Green Lane Project and so much emphasis on cycletracks and protected facilities in the past several years.

Monday, June 3, 2013

This started out as a simple reply on an ITE listserv, but became a blogpost. The discussion centered on traffic engineers being left out of conversations. My thoughts are this:

I used to be defensive about traffic engineering bashing. I would argue and try to dispell the myths. I would think that we're now transportation engineers (not just focused on traffic). It was something that bothered me a bit early in my career.

I found as I worked in many different communities across the country in the private sector that traffic engineers were mostly focused on our own bias and experience. For most of the U.S. this is largely vehicle focused. Most of us drive our cars every day. Some a whole lot further than others. Those that drive a long ways seem to be even more clear on an objective of reducing delays for people in vehicles. This was a challenge for a consultant working for a transit agency trying to implement signal priority.

One of the things I have learned in my career is that it is important to be self aware. Personal bias is part of our problem for our industry. We're often defenders of mobility because that's been our metric. Safety hasn't been as clearly defined, there is a lot of gray area in what constitutes safe conditions.

My experience in the public sector has provided me with another perspective on this that I think is helpful to the community. After working in an agency that is focused on multimodal solutions, it is clear that we (engineers) often have a choice to be part of the solution as opposed to the problem. We are often at our best as problem solvers, working with the community as opposed to telling the community what they can or can't do. Obviously, there are limits, but I have experienced many cases where we tell our fellow professionals what we see as the problem. A better approach is to consider the overarching policy of the agency, the context of the situation, and the unique conditions of the particular community you're working in before we describe the solution. Doing this without personal bias is difficult, but I think that's our job.

In Portland, multimodal safety and neighborhood livability are our main objectives. Our official mission statement is:The City of Portland Bureau of Transportation is a community partner in shaping a livable city. We plan, build, manage and maintain an effective and safe transportation system that provides people and businesses access and mobility. We keep Portland moving.

To go from big picture to details, let me use a signals example. The Flashing Yellow Arrow for left turn operations is a great example of this. It's a tool that could be used to move people more efficiently. So why doesn't the City implement them as a standard?

Years of research (I worked on this as a graduate student) identified the FYA as a new display that would reduce the potential for yellow trap and improve clarity of information to drivers. It also benefits people to reduce delays. The new problem that was created as compared to protected only was that we introduced a condition where left turning vehicles had to yield to pedestrians and people on bicycles. It's not an issue of the Flashing Yellow (the same occurs with a doghouse circular green), but it confirmed what most of us already know: permissive left turns introduce a level of risk from a safety standpoint. Permissive left turns are not inherently bad unless there is a lot of exposure potential and high risk.

One of the challenges of our engineering curriculum is that we have been taught that failure is something to be avoided. Using the Highway Capacity Manual, failure is 80 seconds per vehicle. The problem with this is that in some communities (this may not be yours) the delay should be considered for people and not just vehicles. In downtown settings, there is an interest in prioritizing access for transit or pedestrians and the 80 seconds per vehicle threshold is not the best metric to use to determine effectiveness of a signalized intersection.

My experience in Portland is slightly different than Pete Yauch's in Florida. We get complaints about pedestrian delay and observations from bus operators in addition to folks that are sitting in their cars. Our policies make us put the community first. We want to keep people moving, but safety is our highest goal, so we're balancing those. We have flashing yellow arrows installed cautiously in the City where the safety risk is low for multimodal crashes. We are revisiting the Level of Service standards that put vehicle traffic as the primary measure used to determine adequacy of the transportation system by considering transit and the experience of additional modes. We are looking for ways to reduce costs to our customers, because that's just good government. It is important that we do a better job of prioritizing freight where possible to improve our economic competitiveness. We are context sensitive, solutions orieinted, and focused on serving the citizens.